reversemedium

Randser

spbctf

Task: a 32-bit ELF asks for a serial matching a generated username and UID, then prints a flag. Solution: reverse the PRNG-based login/UID generation, derive the serial formula from the XOR-plus-7 check, and recover the real flag by XOR-reducing 100 hardcoded 16-byte strings.

$ ls tags/ techniques/
static_analysisprng_stream_reconstructionserial_formula_derivationxor_reduction

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